It has been conventional to utilize small screws for attaching various eyeglass frame components together to form a completed frame. Screws have been used to attach temple pieces at the hinge to lens frames. They are also used to tension and anchor or lock lenses into lens frames allowing assembly and disassembly for replacement of lenses or damaged components or initial shipping of frames with demonstration lenses in place.
In normal use, eyeglass frames are subjected to stresses and strains in a cyclical manner that tend to loosen screws and wear the threads with which the screws are mated resulting in temple pieces becoming loose or detached and lenses falling out of their frames.
Various methods to minimize this problem have been tried with limited success. Examples are polymeric compounds often referred to as "locktite" intended to at least slow down the loosening process. This method requires individual coating of the screws which is expensive and provides only limited improvement over uncoated screws eventually succumbing to the same process of loosening. Another example of a method intended to "lock" the screws in place is the use of distorted threads on the screw to create a mechanical jamming action with the mating threads. This method offers only limited improvement and eventually will succumb to the loosening process as well. Both methods make any replacement or disassembly and reassembly process difficult or impossible and do not accommodate wear of the mated components even if loosening or backing out of the screws does not occur.